Device for polishing specimens



April 29, 1969 J, KLElN ET AL 3,440,770

DEVICE FOR POLISHING SPECIMENS Filed. Jan. 31, 1967 Sheet of 2 FIGIApril 29, 1969 J. KLEIN ETAL DEVICE FOR POLISHING SPECIMENS Filed Jan.31, 1967 United States Patent "ice Int. Cl. 1324b /04 U.S. Cl. 51-129 4Claims ABSTRACT OF THE DISCLOSURE The polishing device comprises arotary disc covered with abrasive. The specimens are each retained anddriven in rotation by a wheel rotatably mounted on a stationary plate,the wheels being in frictionally driven contact With a cone which isconcentric with the rotary polishing disc.

This invention is directed to a device for polishing specimens and ismore specifically concerned with polishing devices of the typecomprising a rotary polishing disc having a flat abrasive face at rightangles to its axis of rotation and comprising a substantiallycylindrical plate for retaining specimens to be polished.

Uniform polishing of specimens on a rotating wheel or disc is ensured bysubjecting the specimens to a movement of rotation about their own axesin order to compensate for differences in linear velocities of thepolishing wheel at the different points of the surface to be polished.In order to utilize this inequality of velocities at different points ofcontact and the resultant application on the specimen of a force whichis displaced with respect to the center of its contact sulface, themajority of devices which are in service at the present time accordinglyimpart a movement of rotation to the specimen. In point of fact, themovements of rotation which are thus obtained are not usually uniformand, in addition, there is not even any guarantee that the specimen willbe set in rotation,

The present invention is directed to the design concept of a polishingdevice which meets practical requirements more effectively thancomparable devices of the prior art, especially insofar as it ensures auniform movement of rotation of the specimen without any attendantdanger of jamming, this result being achieved only by the use of simplemechanisms which do not interfere with the positioning and removal ofspecimens. The point last mentioned is important since such operationsare frequently carried out by means of manipulators, particularly whenthe work involves handling of radioactive specimens in hot laboratories.

To this end, the invention proposes a device fitted with a mechanism fordriving specimens in rotation, said mechanism comprising at least onewheel which is driven in rotation by the polishing disc about an axiswhich is parallel to that of said disc, said wheel being placed withrespect to a specimen-insertion hole formed in the plate in such amanner that the frictional contact of the polishing disc with thespecimen moves this latter against the wheel.

In a preferred embodiment of the invention, the mechanism also comprisesa roller which is mounted to rotate freely on said plate on a spindlewhich is parallel to the spindle of the driving wheel, the roller beingplaced with respect to the wheel in such a manner that the specimen isapplied both against said wheel and said roller.

The direction of rotation of the driving wheel and the position of saidwheel with respect to the hole are advantageously chosen so that theaction of the wheel is 3,440,770 Patented Apr. 29, 1969 added to theaction of the difference in linear frictional velocities at thedifferent points of the specimen so as to cooperate in setting thislatter in rotation.

The invention further consists in other arrangements which arepreferably employed in conjunction With the preceding but which can beemployed independently. All of these arrangements will become morereadily apparent from a perusal of the following description of apreferred embodiment of the invention which is given by way ofnon-limitative example, reference being bad to the accompanyingdrawings, in which:

FIG. 1 is a view in elevation of the device with a specimen to bepolished in position;

FIG. 2 shows the device looking on the right-hand side of FIG. 1, thespecimen-holding plate and drive mechanism being in the raised position.

The device which is illustrated in FIGS. 1 and 2 comprises a horizontalbase-plate 4 which carries a drive motor (not shown in the drawings).Said motor is adapted to drive in rotation in the direction of the arrow1 a vertical shaft 6 which carries a rotary polishing disc 8; the topface of the disc is provided with a flat covering 10 of abrasive.

Bearing-brackets 12 are mounted on the base-plate 4 and fitted with ahorizontal pin 14 on which is pivotally mounted a swingable unitgenerally designated by the reference 15; said unit 15 is made up of aplate 16 for receiving and retaining specimens and an arm 18 which ispivotally mounted on the pin 14. The arm and plate are secured to eachother by any suitable means such as screws 20 and shims (not shown)which can be interposed between said arm and said plate so as to modifythe relative positions of these latter and to ensure that the plane ofthe specimen retaining plate and the plane of the base-plate are inparallel relation.

The plate 16 of the device which is illustrated in FIGS. 1 and 2 ispierced by three circular holes such as the hole 22 for the purpose ofaccommodating specimens such as the specimen 24. As shown in FIG. 2, theholes 22 have a diameter which is slightly larger than that of thespecimens in order to permit of a certain freedom of motion in plan whenthe specimen retaining plate is in the lowered position.

The mechanism for driving the specimens in rotation is provided withportions which are associated with each of three holes and a commonportion. Said common portion comprises a driving cone 26 which isrotatably mounted on a spindle 28, said spindle being fixed at thecenter of the specimen retaining plate 16 by means of a nut 29. When thespecimen retaining plate is lowered to the operating position, thedriving cone moves into position in coaxial relation with the rotarypolishing disc, thereby constituting a stationary abutment which fixesthe height of the specimen retaining plate 16 above the abrasivecovering 10. In addition, said cone 26 is adapted to be driven inrotation by the polishing disc. For this purpose, a blind-end slot ofelongated shape is formed in the large base of the cone so as to engageover a tenon 30 of corresponding shape which is formed in the line ofextension of the drive shaft 6.

A driving wheel 32 is associated with the hole 22 and is mounted on aspindle 34 which is secured to the specimen retaining plate. The wheelis mounted to rotate freely on the spindle 34 and is additionallycapable of slidingly longitudinally along said spindle for the purposeof ensuring that a rubber rim 36 which is fitted on said Wheel isbrought to bear against the cone 26 under the action of the weightproper of the wheel. Thus, when the cone, which is driven by thepolishing disc, rotates in the direction of the arrow 1, the wheel 32rotates in the opposite direction (arrow j in FIG. 2).

The driving wheel 32 is placed with respect to the hole 22 in such amanner and has a diameter such that it projects slightly within saidhole 22; as shown in FIG. 2, said wheel is located downstream of thehole in the direction of rotation f of the polishing disc and the wheelspindle 34 is slightly nearer the center of the polishing disc than thecenter of the hole 22.

That portion of the drive mechanism which is associated with the hole 22further comprises a guide roller 38 which is rotatably mounted on avertical spindle 40 which is also secured to the specimen retainingplate 16. Said roller is also placed downstream of the hole 22 in thedirection of rotation of the polishing disc and radially so as toproject also within the hole, the axis of said roller being located at aslightly greater distance from the center of the polishing disc 8 thanthe center of the hole 22.

The operation of the device is apparent from the foregoing descriptionand will therefore be described only briefly. When the unit is in thelowered position, the specimen to be polished is inserted through thehole 22 and placed in position on the polishing disc. As soon as thedisc is set in rotation, the specimen 24 is drawn into abutment againstthe wheel 32 and the roller 38. The wheel 32 then drives the specimen inrotation in the direction indicated by the arrow 1 in FIG. 2, that is tosay in the direction of rotation of the polishing disc 8. Thus, theeffect produced by the difference in linear velocities of the polishingdisc at the different points of contact is added to the action of thewheel 32.

It can therefore be seen that, although the specimen is not subjected toany mechanical connection and no stresses arise other than those whichare exerted on the polishing disc by the sample itself under the actionof its own Weight (to which a suitable ballast-weight may be added),said specimen performs a movement of rotation about its own axis at aconstant speed which ensures uniform polishing.

The device which is illustrated in FIGS. 1 and 2 is designed to receivethree specimens although any number may be provided. In fact, the numberof specimens is limited in practice solely by the dimensions of thepolishing disc. It is noted in addition that the positioning and removalof specimens remain extremely simple operations both during rotation andwhen the device is stationary and the tolerance allowed on the diameterof specimens is as great as was the case in devices of the prior art.

A large number of alternative modes of construction can of course becontemplated. It must be understood that these alternative forms as wellas any others which remain within the scope of equivalent mechanicalmeans are covered by this patent.

What we claim is:

1. A device for polishing specimens of substantially cylindrical shapewherein said device comprises a rotary polishing disc having a fiatabrasive face at right angles to its axis of rotation and a mechanismfor retaining and driving specimens in rotation, said mechanismcomprising at least one roller which is mounted to rotate freely on aspindle which is parallel to the drive shaft of the polishing disc and awheel which is mounted to rotate freely on a spindle which issubstantially parallel to the drive shaft of said polishing disc, saidwheel being applied against and driven by a cone which is coaxial withthe polishing disc and which is disengageably coupled for rotation withsaid disc, the position of the roller and of the wheel being such thatthe friction between the polishing disc and a specimen causes saidspecimen to be applied against said roller and against said Wheel.

2. A polishing device in accordance with claim 1, wherein the wheel isslidably mounted on a spindle carried by a plate and is applied againstthe driving cone under the action of its own Weight.

3. A polishing device in accordance with claim 1, wherein said devicecomprises a plurality of pairs of wheel and roller assemblies which areuniformly spaced around the driving cone and each adapted to drive aspecimen.

4. A polishing device in accordance with claim 3, wherein the drivingcone, wheels and rollers are rotatably mounted on a plate which isswingably mounted on a pivot-pin located at right angles to the axis ofthe polishing disc and the downward application of the cone against thepolishing disc fixes the operating position of the plate in whichopenings are pierced for accommodating specimens.

References Cited UNITED STATES PATENTS LESTER M. SWINGLE, PrimaryExaminer.

